Door catches



March 4, 1969 M. J. JAMES 3,430,999

. DOOR CATCHES Filed Feb. 6, 1967 30 31 QEV 0/ IIIIIIII' Fla 5 Fla. 4.

- INVENTOR Max/4:1. JAS'E /Y dru s BY AT TO RNEYS United States Patent Office 3,430,999 Patented Mar. 4, 1969 3,430,999 DOOR CATCHES Michael Joseph James, Cheltenharn, England, assignor to Micro and Precision Mouldings (Cheltenham) Limited, Cheltenham, England Filed Feb. 6, 1967, Ser. No. 614,163 Claims priority, application Great Britain, Feb. 5, 1966,

5,163/ 66 US. Cl. 2275 Int. Cl. E05c 19/04 8 Claims ABSTRACT OF THE DISCLOSURE This invention relates to roller door catches of the type comprising a housing in which a plunger is slidably mounted, the plunger being spring loaded to a position in which a roller at the outer end of the plunger projects from the housing for engagement with a keeper mounted on the door frame.

Catches of this nature are commonly provided with means which allow the free outward projection of the plunger to be adjusted, sometimes only when initially fitted but often also during use. The object of the invention is to provide a roller door catch which is automatically self-adjusting in use, so that the outward projection of the plunger remains at the correct value to suit the spacing between the door and frame.

To this end the plunger of a roller door catch in accordance with the invention is mounted in the housing with a degree of free angular play about its longitudinal axis and is screw-threaded for engagement by a stop member formed with a clutch face for frictional engagement with a fixed clutch face, such engagement acting to limit outward movement of the plunger under spring loading thereof, a fixed stop face in the housing being engageable by the stop member on inward movement of the plunger to prevent further inward movement of the stop member, and the frictional engagement of the clutch faces under the spring loading being such that the clutch slips at a lower torque than that necessary to screw the stop member up the thread.

It will be appreciated that a screw thread of fairly large pitch will normally have to be used to provide the necessary torque characteristics enumerated above, and this is particularly so if the various elements of the catch are moulded from a low friction material such as nylon when the thread is conveniently of square profile. The clutch faces are conveniently of mating frusto-conical form to provide a cone clutch arrangement.

The catch adjusts itself in the following manner. When the door is open the plunger takes up a projecting position defined by engagement of the stop member with the fixed clutch :face, the spring force tending to extend the screw threaded engagement with the stop member so that the plunger is turned to take up ,the angular clearance with the housing in the appropriate direction. On door closure initial engagement of the plunger roller with a keeper mounted on the door frame turns the plunger so that it straightens up within the housing, the lateral force applied to the plunger urging the latter against the trailing side of the housing. This tends to screw the plunger in which respect to the stop member, but due to the aforesaid torque relationship the clutch slips before the thread takes up so that no screw thread adjustment occurs.

As door closure continues the plunger moves into the housing and the stop member strikes the fixed stop face to limit inward movement of the stop member to a predetermined amount dependent on the spacing between the fixed clutch face and the fixed stop face, the amount of this movement being the desired plunger stroke. Further inward movement of the plunger after movement of the stop member has been limited is accommodated by the screw thread and accompanying rotation of the stop member. When the door is fully closed the plunger moves out to engage the keeper, normally without the stop member returning into engagement with the fixed clutch face.

When the door is opened the plunger is again initially straightened up in the housing, and as soon as free of the keeper the plunger moves out, still in the straightened up position, until the stop member engages the fixed clutch face. It is an inherent characteristics of friction clutches that some slipping occurs on initial engagement, and the initial clutch slip allows a slight extension of the screw threaded engagement thus adjusting the plunger a small amount outwardly. The spring again acts to turn the plunger in a direction corresponding to extension of the screw threaded engagement to the limit allowed by the angular clearance in the housing, and this results in a further outward adjustment as the clutch does not now slip.

It will thus be seen that on door closure the position of the stop member with respect to the plunger is adjusted to correct the plunger stroke, on door opening two small outward increments of adjustment being provided. If not required these increments are cancelled by corresponding adjustment of the stop member on the next door closure, and the arrangement may be such that when initially fitted to the first door closure provides full adjustment if the plunger projection is excessive, continuous adjustment thereafter being provided to accommodate dimensional variations in the door and door frame structure.

The plunger conveniently has a hollow stem formed with an internal screw thread, in which case the stop member is conveniently in the form of a headed stud which screws into the stem with the under surface of the head providing the clutch face of the stop member. The fixed stop face is conveniently provided by an inner end wall of the housing, and the head of the stop member preferably has a central domed projection which engages the end wall.

The fixed clutch face may be provided at the inner end of a tubular limit or abutment member which fits in the housing, and this member conveniently has lateral locating projections which snap into locating apertures in the housing to retain the abutment member in position, during assembly the member being inserted through the outer end opening of the housing. This construction materially facilitates assembly as all the internal elements of the catch, namely the plunger stop member, spring and abutment member can initially be assembled to form a subassembly which is then merely inserted into the housing until the locating projections snap into position.

The abutment member conveniently provides a limiting abutment which provides an overriding limit for the maximum outward projection of the roller in the event of the stop member being screwed too far out of the plunger. The limiting abutment may be provided by inwardly projecting lips at the outer end of the abutment member behind which projections on the inner end of the plunger stem engage, and this not only holds the plunger in the abutment member with the spring in position during initial assembly before the stop member is. fitted but also prevents any possibility of the stop member becoming completely unscrewed and the plunger ejected by the spring during service. The projecting lips may also provide a bearing for the stem of the plunger and hence also assist in guiding sliding movement of the later.

The invention will now be further described with reference to the accompanying drawings which illustrate, by way of example, a roller door catch in accordance with the invention.

In the drawings:

FIGURE 1 is an outer end view of the catch,

FIGURE 2 is a sectional view on the line IIII in FIGURE 1,

FIGURE 3 is a sectional view on the line III-1H in FIGURE 2,

FIGURE 4 is a face view of a suitable form of striker and keeper for use with the illustrated catch, and

FIGURE 5 is a sectional view on the line VV in FIGURE 4.

The catch has a moulded housing 1 of tubular form with an outer end fixing flange 2 enabling it to be mortised into the shut face of a door in the usual manner. A plunger 3 has an outer end head 4 and a cylindrical hollow stem 5 of reduced diameter, the head forming a yoke within which a barrel-shaped roller 6 is rotatably mounted about a vertical axis X-X. A return spring 7 positioned between the head 4 of the plunger and a fixed abut ment member 8 urges the plunger 3 to a resting position in which the roller 6 projects from the open outer end of the housing 1 in the usual manner.

The abutment member 8 is of tubular form and surrounds the plunger stem 5 which is formed with an internal screw thread 9 of square profile. A stop member 10 is in the form of a headed stud and has a threaded stem 12, which engages the screw thread 9 in the plunger stem 5, and a head under surface 13 which is frusto-conical to provide a clutch face. This face engages a frusto-conical seating 14 in the inner end of the abutment member 8 which forms a fixed clutch face. Engagement of the stop member 10 with the abutment member 8 not only provides friction clutch means but also serves to limit the adjusted outward projection of the plunger 3 and hence defines the resting position of the latter.

All the parts of the catch so far described are moulded from nylon, with the exception of the return spring 7. The yoke arms of the plunger head 4 slide in upper and lower guideways 15 which are moulded within the housing 1, and reciprocation within the housing is additionally guided by engagement of the plunger stem 5 with inwardly projecting lips 16 of arcuate form moulded at the outer end of the abutment member 8. The circumferential spacing between the guide lips 16 is somewhat greater than the circumferential extent of each of two diametrically opposed projections 17 moulded at the inner end of the plunger stem 5 and which in the assembled catch are able to engage behind the guide lips 16 to provide an overriding limiting abutment preventing excessive outward projection of the plunger 3.

During assembly the plunger 3 is fitted into the abutment member 8 so that the projections 17 pass between the guide lips 16, the plunger 3 thereafter being turned to the final position. At the inner end the abutment member 8 is moulded with an outer flange 18 with projections 19 which engage the guideways 15 in the housing 1 and also on assembly spring outwards into engagement with locating apertures 20 in the wall of the housing 1, thus locating the abutment member 8 firmly and accurately in position. After fitting the plunger 3 to the abutment member 8 in the described manner, with the spring 7 in position, the stop member 10 is screwed into the plunger stem 5 to provide a complete sub-assembly of all the elements of the catch before the abutment member 8 is finally fitted into the housing 1.

The plunger head 4 has a small 13? l tt ral clearance in the guideways 15 in the housing, to provide in accordance with the invention a small degree of free angular movement of the plunger 3 within the housing about the longitudinal axis of the plunger. The actual value of this free angular movement is not important but it is conveniently of the order of 1 to 2.

The upper, or inner end, face or the head of the stop member 10 has a central part-spherical projection 22 which engages the inner end wall 23 of the housing 1 which provides a fixed stop face to limit inward movement of the stop member, the maximum movement of the stop member 10 from engagement with the abutment member 8 into contact with the inner end wall 23 corresponding to the desired normal stroke of the plunger 3. As previously mentioned, the characteristics of the friction clutch means 13, 14 must be such that the clutch slips at a torque lower than that necessary to screw the stop member 10 into the plunger stem 5 against the return force exerted by the spring 7. In one particular example with the parts moulded from nylon, this requirement is satisfied with clutch faces such as 13, 14 having an included cone angle of and a thread pitch of 4 t.p.i

The outward projection of the plunger 3 from the housing 1 adjusts itself automatically on door opening and closure in the manner already described. Thus on closure the stop member 10 strikes the end wall 23 of the housing if the inward plunger stroke is excessive and thus limits the resultant outward plunger movement. On subsequent door opening the clutch 13, 14 slips to provide a small outward movement increment after the stop member 10 engages the abutment member 8, and turning of the plunger 3 within the housing 1 as a result of the spring force and screw thread provides a further outward increment. In the described example the free movement of the stop member 10 between the abutment member 8 and the housing end wall 23 is "94 inch and the two adjustment increments are each of the order of 5 thousandths of an inch. Thus if the gap between the door and door frame increases, on closure the stop member 10 will not engage the housing end wall 23 and on each subsequent door opening the plunger 3 will adjust out a total of 10 thousandths of an inch until the increased spacing has been accommodated and the stop member 10 again strikes the housing end wall 23 on closure. As long as the spacing remains constant, adjustment of the stop member 10 on each door closure cancels the two increments of previous door opening. Should the door and frame spacing decrease this is compensated for in one action on door closure by adjustment of the stop member 10. In a typical embodiment a range of adjustment of the order of inch can readily be obtained.

The keeper 30 shown in FIGURES 4 and 5 has a ramplike leading edge portion 31 which initially engages the roller 6 on door closure to displace the plunger 3 inwardly. The inward displacement continues until the roller 6 enters a recess 32 in the keeper and within which it engages, under the force of the spring 7, to hold the door closed.

I claim:

1. A roller door catch of the type specified wherein the plunger is mounted in the housing with a degree of free angular play about its longitudinal axis and is screwthreaded for engagement by a stop member formed with a clutch face for frictional engagement with a fixed clutch face, such engagement acting to limit outward movement of the plunger under spring loading thereof, a fixed stop face in the housing being engageable by the stop member on inward movement of the plunger to prevent further inward movement of the stop member and the frictional engagement of the clutch faces under the spring loading being such that the clutch slips at a lower torque than that necessary to screw the stop member up the thread.

2. A roller door catch according to claim 1, wherein the clutchfaces are of mating frusto-conical form to provide a one clutch arrangement.

3. A roller door catch according to claim 1 wherein the plunger has a hollow stem formed with an internal screw thread and the stop member is in the form of a headed stud which screws into the stem with the under surface of the head providing the clutch face of the stop member.

4. A roller door catch according to claim 3, wherein the fixed stop face is provided by an inner end wall of the housing, and the head of the stop member has a central domed projection which engages the end wall.

5. A roller door catch according to claim 1, wherein the fixed clutch face is provided at the inner end of a tubular abutment member which fits in the housing and has lateral locating projections which snap into locating apertures int he housing to retain the abutment member in position, during assembly the abutment member being inserted through the outer end opening of the housing.

6. A roller door catch according to claim 5, wherein the abutment member provides a limiting abutment which provides an overriding limit for the maximum out-ward projection of the roller.

References Cited UNITED STATES PATENTS 2,541,720 2/1951 Robinson 292-75 3,031,220 4/ 1962 Reiss 292-75 3,133,757 5/1964 James 292--75 3,322,450 5/ 1967 Russell et a1. 292-75 MARVIN A. CHAMPION, Primary Examiner.

J. R. MOSES, Assistant Examiner. 

